Stillbirth is a significant contributor to severe maternal morbidity (SMM), according to a recent study published in the American Journal of Obstetrics & Gynecology.
Takeaways
- The study highlights a significant gap in understanding the impact of stillbirth on maternal health, revealing an increased risk of severe maternal morbidity (SMM) not only during delivery but also extending into the prenatal period and up to a year postpartum.
- SMM rates have surged by 14.7% from 2012 to 2019, with factors such as maternal age, clinical conditions, obesity, and pregnancy complications contributing to this concerning trend.
- Approximately 21,000 stillbirths occur annually in the United States, underlining the importance of investigating its ramifications on maternal health.
- Patients experiencing stillbirth were more frequently associated with risk factors such as smoking, non-Hispanic Black ethnicity, Medicaid insurance, and preexisting health conditions such as diabetes mellitus and hypertension.
- Adjusted relative risk analysis indicates a 4-fold higher risk of SMM among patients with stillbirth compared to those with livebirth, emphasizing the need for targeted interventions and support for this vulnerable population.
SMM, associated with short- and long-term health consequences, has risen in incidence over time, with a 14.7% increase observed from 2012 to 2019. Factors contributing to this rise include maternal age, clinical conditions, obesity, and pregnancy complications.
In the United States, approximately 21,000 stillbirths are reported per year, at a rate of 57 fetal deaths per 10,000 live births and fetal deaths. However, while evidence evaluating the association between maternal characteristics and SMM has grown, there is limited data about the impact of stillbirth on SMM.
Investigators conducted a multistate analysis to determine the relative risk (RR) of SMM among patients with stillbirth vs livebirth deliveries. Data from birth and fetal death records from Missouri, Michigan, South Carolina, Pennsylvania, and California were included in the analysis.
Births from 22 to 44 weeks’ gestation were evaluated. Exclusion criteria included the inability to link birth or fetal death certificate to maternal discharge data, missing data, and not being the first birth of patients with multiple pregnancies.
SMM and SMM excluding blood transfusions during the delivery hospitalization were reported as the primary outcomes of the analysis. Secondary outcomes included SMM and nontransfusion SMM during pregnancy or within 42 or 365 days after pregnancy.
SMM was determined based on International Classification of Diseases, Ninth Revision (ICD-9) or ICD-10 codes. Conditions classified under SMM included 16 life-threatening maternal conditions and 5 life-saving procedures. Gestational age was determined using available obstetrical estimates or the last menstrual period estimate.
Patients with stillbirth were more often smokers, non-Hispanic Black, had missing educational status, had Medicaid insurance, and had higher rates of preexisting diabetes mellitus, preexisting hypertension, preeclampsia, and multiple pregnancies than those with livebirth. These patients also had higher SMM, nontransfusion SMM, and comorbidity index score.
Stillbirth was associated with increased rates of SMM starting at 31 weeks’ gestation and nontransfusion SMM starting at 30 weeks’ gestation. Overall, the prevalence of SMM and nontransfusion SMM among patients with stillbirth were 791 and 502 per 10,000 deliveries, respectively, vs 154 and 68 per 10,000 deliveries, respectively, among patients with livebirth.
After adjustment for maternal sociodemographic factors, a 4-fold higher risk of SMM was reported among patients with stillbirth vs those with livebirth, with a transfusion SMM adjusted RR (aRR) of 3.8 and nontransfusion SMM aRR of 5.1. These aRRs were 1.6 and 2, respectively, after adjusting for an obstetric comorbidity index.
When adjusting for maternal sociodemographic characteristics and pregnancy complications instead of a comorbidity index, the risk of SMM remained higher for stillbirth vs livebirth, with transfusion SMM and nontransfusion SMM aRRs of 3.5 and 4.5, respectively. The risks of all SMM indicators except for heart failure were greater among patients with stillbirth.
These results indicated an increased risk of SMM among patients with stillbirth. Investigators concluded SMM risk is increased not only during the delivery hospitalization but also at any time during the prenatal period and up to 1 year following delivery.
Reference
Nyarko SH, Greenberg LT, Phibbs CS, et al. Association between stillbirth and severe maternal morbidity. Am J Obstet Gynecol. 2024;230:364.e1-14. doi:10.1016/j.ajog.2023.08.029
